51. As you have seen, the values of a nation's currency is a _____ of its economy.
　　A) reaction
　　B) reflection
　　C) response
　　D) revelation
　　52. In the Spring Export Commodities Fair the ______ of fine china attracted much attention of customers from all over the world.
　　A) succession
　　B) array
　　C) string
　　D) procession
　　53. We should make a clear _______ between the two scientific terms for the purpose of our discussion.
　　A) separation
　　B) discrimination
　　C) deviation
　　D) distinction
　　54. The terrorists might have planted a bomb on a plane in Athens, set to ______ when it arrived in New York.
　　A) go off
　　B) get off
　　C) come off
　　D) carry off
　　55. We should be able to do the job for you quickly, ______ you give us all the necessary information.
　　A) in case
　　B) provided that
　　C) or else
　　D) as if
　　56. The younger person's attraction to stereos cannot be explained only _____ familiarity with technology.
　　A) in quest of
　　B) by means of
　　C) in terms of
　　D) by virtue of

　　57. Attempts to persuade her to stay after she felt insulted were ______.
　　A) in no way
　　B) on the contrary
　　C) at a loss
　　D) of no avail
　　58. By signing the lease we made a _______ to pay a rent of '150 a week.
　　A) conception
　　B) commission
　　C) commitment
　　D) confinement
　　59. To prevent flooding in winter the water flowing from the dam is constantly ______ by a computer.
　　A) graded
　　B) managed
　　C) conducted
　　D) monitored
　　60. Many people think of deserts as _____ regions, but numerous species of plants and animals have adapted to life there.
　　A) virgin
　　B) barren
　　C) void
　　D) wretched